Jonathan Martin Surrenders to Police

3/20/2018 3:33 PM PDT

imageFormer NFL lineman Jonathan Martin turned himself in to police Tuesday ... TMZ has learned.

Martin has been charged with 4 felonies -- 4 counts of making criminal threats. He's also been charged with 1 misdemeanor for carrying a loaded firearm in a vehicle.

Martin has pled not guilty.

The surrenders follows a bizarre incident on February 22, where Martin posted a photo of a shotgun and ammo with the message, "When you're a bully victim and a coward, you're options are suicide, or revenge."

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